VALENCE BANDS OF THE CU-III-VI2 CHALCOPYRITES STUDIED BY PHOTOEMISSION SPECTRA, X-RAY-EMISSION SPECTRA, AND ELECTRONIC-STRUCTURE CALCULATIONS

Ultraviolet and X-ray excited photoemission spectra and Cu K beta //5 X-ray emission spectra are used to measure the valence band density of states in CuGaTe//2 and CuInTe//2. In both compounds the density of states exhibits five structures which are ascribed to Cu 3d-Te 5p hybridized states, Ge 4s/In 5s-Te 5p bonding states, and Te 5s states. The valence band density of states of all Ga- and In-containing Cu-III-VI//2 is calculated in an atomic orbital basis with the noble metal d states explicitly included. The agreement between theory and experiment is good for CuGaTe//2 and except the In 5s-VI p bonding states also for the Cu-In-VI//2 chalcopyrites. Larger discrepancies between theory and experiment are found for CuGaS//2 and CuGaSe//2.